Green and facile synthesis of carboxymethylcellulose/ZnO nanocomposite hydrogels crosslinked with Zn²⁺ ions

A green method was used for the preparation of functional carboxymethyl cellulose (CMC) hydrogel crosslinked by divalent zinc ions and incorporated with zinc oxide nanoparticles (ZnO) without using alkaline reagents. In the process, sodium carboxymethyl cellulose was used not only as a hydrogel matrix but also for the release of free hydroxyl groups, which increases the pH of the reaction mixture, consequently leading to the formation of ZnO. The chemical structure and morphology of the hydrogels were characterized using FTIR and FE-SEM analysis, respectively. The water absorption capacity of the hydrogels was studied as a function of temperature and pH. The results of FE-SEM showed the formation of ZnO particles in the hydrogel, while the water absorption capacity results supported the formation of zinc ion cross-linking within the carboxymethylcellulose chains. The CMC/ZnO nanocomposite hydrogel exhibited strong antimicrobial activity against pathogenic bacteria E. coli and L. monocytogenes.